1. Field
The following description relates to a technology that manages/operates radio resources used for transmission/reception of information associated with a wireless environment of terminals, a signal for synchronization, and control information of base stations.
2. Description of Related Art
Recently, a communication technology that uses a small cell such as a femtocell and a picocell has rapidly developed. A femtocell is a small cellular base station, typically designed for use in a home or small business. A picocell is a wireless communication system typically covering a small area, such as within a building, or in a vehicle, such as an airplane. A picocell is analogous to a Wi-Fi access point.
As new communication systems including the small cell are developed, research on technologies, such as interference alignment, dynamic spectrum management, interference control, etc., for interference control is continuously performed to develop schemes that overcome an interference occurring between the small cells or an interference occurring between the small cell and a macrocell. In addition, a technology that controls a topology of a network including a plurality of cells is also considered to be important. Examples of topologies of the network may include a bus type, a ring type, a star type, a tree type, a message type, etc.
To perform the interference control or topology control, it is desirable that terminals and base stations effectively perform transmission/reception of a variety of information. In this case, there is a desire for a technology that effectively manages/operates radio resources used for the transmission/reception of the information between the terminals and the base stations.
Also, in general, each of the base stations performs transmission/reception of the information with a terminal in a corresponding cell or with a predetermined terminal. When each of the base stations performs transmission/reception of the information with a terminal in another cell or with all terminals, sufficient information may be collected for optimal interference control or optimal topology control.
FIG. 1 illustrates a first example 110 in which information associated with a wireless environment is transmitted/received in each cell and a second example 120 in which the information associated with a wireless environment is transmitted/received between cells.
Referring to the first example 110 of FIG. 1, a cell 111 may include a base station 1 (BS1) and a terminal 1 (MS1), and a cell 112 may include a base station 2 (BS2) and a terminal 2 (MS2). Uplink control information, (hereinafter “uplink feedback information”), downlink control information (hereinafter “broadcasting information”), and control signaling, as an example, a pilot, sounding, etc., may be transmitted/received between the BS1 and the MS1. In the same manner, the uplink feedback information, the downlink control information, the control signaling, etc., may be transmitted/received between the BS2 and the MS2. In the first example 110, each of the MS1 and the MS2 may perform transmission/reception of the uplink feedback information, the downlink control information, the control signaling, etc., with a corresponding service base station. In this instance, each of the BS1 and the BS2 may individually allocate radio resources for a corresponding terminal. That is, the BS1 may independently allocate radio resources to the MS1 to perform transmission/reception with the MS1, and also, the BS2 may independently allocate radio resources to the MS2 to perform transmission/reception with the MS2. Information may be exchanged between cells to control a network topology and inter-cell interference. However, a communication system of the first example 110 may not consider inter-cell information exchange, and thus control of the network topology and the inter-cell interference may not be effectively performed. As an example, when the BS1 does not recognize information associated with a wireless environment between the BS1 and the MS2, for example, information associated with a channel and information associated with a mobility of the MS2, and the like, and the BS2 does not recognize information associated with a wireless environment between the BS2 and the MS1, cooperation between the cell 111 and the cell 112 may not be expected.
Referring to the second example 120 of FIG. 1, a cell 121 may include a base station 1 (BS1), a terminal 1 (MS1), a terminal 2 (MS2) and a cell 122 may include a base station 2 (BS2) and the terminal 2 (MS2).
The two cells 121 and 122 are cooperating in the second example 120. The MS2 located in a boundary of the two cells 121 and 122 simultaneously transmits uplink feedback information to the BS1 and the BS2. Also, the MS2 may receive downlink control information from the single BS1. In the second example 120, only the MS2 located in the boundary may transmit the uplink feedback information to the BS1 and the BS2, and the MS1 may transmit only to the BS1. That is, when a portion of terminals transmits uplink feedback information to all base stations, uplink feedback information of remaining terminals may not be appropriately shared, and thus, a topology control or an interference control may be difficult to be performed optimally in an entire communication system.
Accordingly, all terminals are desired to transmit corresponding uplink feedback information to all base stations, and effective allocation of limited radio resource to each of the terminals is important for each of the terminals to transmit the corresponding uplink feedback information to the all base stations.
Example embodiments define a “common operating set” where a multi-cell common operation related to the interference control or the network topology control is performed, and separately manages the “common radio resources” for a plurality of cells in the common operating set. Unique uplink radio resources for terminals in the common operating set may also be allocated within the common radio resources. Each of the terminals may transmit corresponding uplink feedback information to all base stations using corresponding unique uplink radio resources. In this instance, each of the base stations may receive uplink feedback information from all the terminals, and a central controlling apparatus may collect the uplink feedback information received by the base stations. Accordingly, the central controlling apparatus may recognize all information associated with a wireless environment between each of the terminals and each of the base stations, and thus, an optimal topology control and an optimal interference control may be performed. As an example, in the second example 120 of FIG. 1, the central controlling apparatus according to example embodiments may recognize all information associated with a wireless environment between the MS1 and the BS1, between the MS1 and the BS2, between the MS2 and the BS1, and between MS2 and BS2.